Federal clean water requirements require water bodies such as lakes and rivers that must meet strict minimal water quality specifications. To achieve these requirements, storm water drainage pipes often require treatment before conveying storm water into receiving water bodies. As a result, a wide variety of technologies have been developed to treat storm water and improve the water quality.
Common storm water treatment systems are hydrodynamic separators such as baffle type boxes and vortex systems. Hydrodynamic separators can treat relatively large water flows and are good for removing solids that are relatively large in size. However, these types of systems are limited to the size of the pollutants being removed, and are not very efficient for removing dissolved pollutants such as dissolved phosphorus and nitrogen, etc.
To achieve water treatment beyond what can be accomplished by a hydrodynamic separator, another class of storm water treatment systems commonly referred to as filtration systems are used. Filtration systems typically will pass the water flow through a filter media such as sand, zeolite, activated carbon, and the like. Filter media is typically selected to do more than remove solids from the water flow. Depending on the pollutants of concern, filter media can be selected to remove specific dissolved pollutants such as nutrients, metals, or a wide variety of chemical contaminates.
However, a problem with using filter media in a storm water treatment system is the significant influence of friction between the water and the media. In addition, changing the direction of water flow as it passes through a filtration system reduces the kinetic energy of the water flow which will reduce the volume water flow. During big rain events a storm water filtration system in a storm water pipe can significantly inhibit the passage of water and cause flooding upstream from the filtration system. If the filtration system becomes clogged with debris the water flow can be completely stopped.
Typical filter media treatment has required the use of cartridge systems. See for example, U.S. Pat. No. 8,658,044 to Cobb, assigned to Contech Engineered Solutions LLC, and U.S. Published Patent Application 2015/0129473 to Kent. Generally in these types of systems, multiple individual cartridges are filled with media. Water flow is then passed through each of the cartridges and the cartridges collectively treat the water flow. The problem is that the size of the cartridges are limited to a size that can be removed from the vault during servicing. Additionally, there are void spaces between the cartridges, and these spaces are not able to be engaged in the treatment process.
The inventor of the subject application has used media in filters inside of storm water vaults. See for example, U.S. Pat. Nos. 8,034,234 and 8,231,780 to Happel, which are both incorporated by reference. In these patents filtration media cartridges are not being used. However, these patents and all the prior art have additional problems of what happens to the debris which will land spread out across the entire floor of the vault. Having to service debris that is located everywhere on the floor makes it difficult and time consuming to later remove that debris. For example, vacuum lines would need to be used throughout the entire floor. Additionally, the debris can remain in large sizes.
Thus, the need exists for solutions to the above problems with the prior art.